mediatek: filogic: add support ASUS RT-AX59U

mediatek: filogic: add support ASUS RT-AX59U

(based on support for ASUS RT-AX59U by liushiyou006)

SOC: MediaTek MT7986
RAM: 512MB DDR4
FLASH: 128MB SPI-NAND (Winbond W25N01GV)
WIFI: Mediatek MT7986 DBDC 802.11ax 2.4/5 GHz
ETH: MediaTek MT7531 Switch
UART: 3V3 115200 8N1 (Pinout silkscreened / Do not connect VCC)

Upgrade from AsusWRT to OpenWRT using UART

    Download the OpenWrt initramfs image.
    Copy the image to a TFTP server reachable at 192.168.1.70/24. Rename the image to rtax59u.bin.

    Connect the PC with TFTP server to the RT-AX59U.
    Set a static ip on the ethernet interface of your PC.
    (ip address: 192.168.1.70, subnet mask:255.255.255.0)
    Conect to the serial console, interrupt the autoboot process by pressing '4' when prompted.

    Download & Boot the OpenWrt initramfs image.

    $ setenv ipaddr 192.168.1.1
    $ setenv serverip 192.168.1.70
    $ tftpboot 0x46000000 rtax59u.bin
    $ bootm 0x46000000

    Wait for OpenWrt to boot. Transfer the sysupgrade image to the device using scp and install using sysupgrade.

    $ sysupgrade -n <path-to-sysupgrade.bin>

Upgrade from AsusWRT to OpenWRT using WebUI

    Download transit TRX file from https://drive.google.com/drive/folders/1A20QdjK7Udagu31FSszpWAk8-cGlCwsq

    Upgrade firmware from WebUI (192.168.50.1) using downloaded TRX file

    Wait for OpenWRT to boot (192.168.1.1).

    Upgrade system with sysupgrade image using luci or uploading it through scp and executing sysupgrade command

MAC Address for WLAN 5g is not following the same algorithm as in AsusWRT.
We have increased by one the WLAN 5g to avoid collisions with other networks from WLAN 2g
when bit 28 is already set.

              : Stock             : OpenWrt
  WLAN 2g (1) : C8:xx:xx:0D:xx:D4 : C8:xx:xx:0D:xx:D4
  WLAN 2g (2) :                   : CA:xx:xx:0D:xx:D4
  WLAN 2g (3) :                   : CE:xx:xx:0D:xx:D4
  WLAN 5g (1) : CA:xx:xx:1D:xx:D4 : CA:xx:xx:1D:xx:D5
  WLAN 5g (2) :                   : CE:xx:xx:1D:xx:D5
  WLAN 5g (3) :                   : C2:xx:xx:1D:xx:D5

  WLAN 2g (1) : 08:xx:xx:76:xx:BE : 08:xx:xx:76:xx:BE
  WLAN 2g (2) :                   : 0A:xx:xx:76:xx:BE
  WLAN 2g (3) :                   : 0E:xx:xx:76:xx:BE
  WLAN 5g (1) : 0A:xx:xx:76:xx:BE : 0A:xx:xx:76:xx:BF
  WLAN 5g (2) :                   : 0E:xx:xx:76:xx:BF
  WLAN 5g (3) :                   : 02:xx:xx:76:xx:BF

Signed-off-by: Xavier Franquet <xavier@franquet.es>